1. Field of Invention
This invention relates to a highly compact all-channel television antenna. More particularly, it relates to an all-channel television antenna having the antenna elements the same physical length.
2. Discussion of the Prior Art
Over the past several decades, the art of television antenna design has become quite sophisticated. Two general consumer categories of antennas have evolved. The first category contains the "multi-element" UHF-VHF large antennas which typically comprise numerous elements in each antenna in order to improve the gain and directivity of the television signal across the 82 channel VHF-UHF bands. Examples of such prior art approaches are:
______________________________________ U.S. Pat. No. Inventor Date ______________________________________ 3,531,805 Winegard et al Sept. 29, 1970 3,475,759 Winegard Oct. 28, 1969 3,329,960 Winegard July 4, 1967 3,007,167 Winegard Oct. 31, 1961 2,992,430 Winegard July 11, 1961 3,321,764 Winegard et al May 23, 1967 ______________________________________
One such prior art approach is conventionally available from the WINEGARD COMPANY known as the CHROMSTAR VHF-UHF line of antennas. The largest of this series is the Model CH-8200 (U.S. Pat. No. 2,992,430) comprising a total of 43 elements (29 UHF elements and 22 VHF elements) having a boom length of 173 inches, a turning radius of 98 inches, and a maximum width of 108 inches. The smallest UHF-VHF antenna in the CHROMSTAR series is the Model CH-7074 having a total of seven elements (4 VHF and 3 UHF) with a boom length of 341/2 inches, a turning radius of 56 inches, and a maximum width of 108 inches.
In the conventionally available GOLD STAR line from the WINEGARD COMPANY, the VHF portion of the antennas are substantially "V" types and the smallest UHF-VHF antenna in this series has a total of ten elements (3 VHF and 7 UHF) with a boom length of 263/4 inches, a turning radius of 481/2 inches, and a maximum width of 89 inches.
Another series of conventionally available "multi-element" large antennas available from the WINEGARD COMPANY are called PREMIER "X" and these antennas intermix both VHF and UHF signals on the same linear plane. The smallest UHF-VHF antenna in this series has five elements (Model X-15).
The second general category of consumer VHF-UHF television antennas may properly be termed "rabbit-ears." The WINEGARD COMPANY also manufactures a conventional series of VHF-UHF indoor antennas known as the COLOR CEPTOR line and the POWERBEAM line. All of these prior art approaches are designed to have a base member which preferably sets on the top of a television set with at least two upstanding adjustable antenna elements affixed thereto. In addition, a UHF upstanding circular element may also be provided. Rabbit ear antennas, however, are not known for significant response.
A consumer antenna nearing (or approaching) the performance of the large multi-element antennas, yet combining the size and lightweight of the small rabbit-ears antennas would form a third classification of consumer VHF-UHF television antennas. The SENSAR line conventionally available from WINEGARD COMPANY (Models Sr-20A, SR-30M, and RVH-2K) properly falls in this category.
The Radio Corporation of America (RCA) also manufactures an antenna in this third consumer category which is identified as Model 5MS550 and termed the AC-DC MINISTATE ANTENNA SYSTEM. The RCA system contains a miniaturized uni-directional antenna, a solid state amplifier and an electrical rotating mechanism all housed inside a weather-proof housing. The diameter of the housing of the RCA system is 201/2 inches. The VHF section of the RCA system is a circular shaped, slot tune, broad band, uni-directional traveling wave antenna. The UHF section, on the other hand, is a broad band multi-element array. The VHF signal must be amplified and then is combined with an unamplified UHF signal by means of an adder circuit.
The present invention more properly falls in the third category of consumer antennas. The antenna system of the present invention performs like a large multi-element antenna twice its size yet maintains the compactness and lightweightness of the rabbit-ear consumer category. Like the RCA antenna system, the antenna system of the present invention utilizes a unique weather-tight housing and can optionally contain a rotor for rotating the antenna, and a preamplifier circuit. Unlike the RCA system, the preamplifier is not necessary for operation of the antenna. The rotor is protected against dirt and weather for long life and enables the antenna to rotate substantially 360.degree.. More importantly, and in contrast to the RCA system, the antenna system of the present invention utilizes outwardly extending antenna elements for the entire VHF-UHF band. Unlike the large television antennas of the first category, the antenna system of the present invention utilizes no horizontal cross-arms or booms, as conventionally termed, and hence does not require conventional saddle supports of insulating materials or the like. However, since the antenna of the present invention does utilize outwardly extending antenna elements, these elements are positively locked to substantially minimize sagging, and/or misaligning due to windloading, icing, and the like.
Most fundamentally, the antenna system of the present invention contains six outwardly extending antenna halves forming three elements, each having the same physical length. No prior art all band VHF-UHF television antenna utilizes such an element configuration. From a manufacturing and cost viewpoint, the antenna system of the present invention represents a major breakthrough. Only one size of element need be manufactured and stocked.
The six element halves are combined into three elements wherein the first and second elements are utilized primarily to receive a VHF signal in the low band and wherein the second and third elements are utilized primarily to receive signals in the high VHF band. The physical spacing between each element is substantially the same and is substantially less than one-tenth of a wave length of the shortest VHF wave length.
The VHF frequency range includes a low VHF band of 54 mHz to 88 mHz (channels 2-6) and a high VHF band of 174 mHz to 216 mHz (channels 7-13). Hence the shortest wavelength in the VHF range occurs at 216 mHz with 54.3"--the one-tenth wavelength being 5.43". Conventionally the spacings between the VHF antenna elements may be a quarter wavelength (i.e., 13.6") and the element halves are interconnected in a crossover fashion (front fed) so that the combined signals are in phase to be additive. As set forth in U.S. Pat. No. 3,392,399 (issued to WINEGARD on July 9, 1968) the spacings between the driven VHF dipoles can be reduced to minimum spacing of approximately one-tenth of a wavelength with reference to the high end of the high VHF band. Hence, spacings of 5.75 inches were achieved by using a transmission line having a series of serpentine or sinusoidal convolutions formed in a plane parallel to the plane of the dipole elements. The antenna of the present invention achieves a spacing between the driven elements substantially less than one-tenth of a wavelength with respect to the same reference. Again, the high degree of compactness of the antenna system of the present invention is due in part to the close physical spacing between the elements as taught in the present invention. This contributes significantly to the overall compactness of the antenna and the lightweightness of the antenna. Significant breakthroughs in manufacturing costs are also obtained.
As a result, the all band UHF-VHF antenna system of the present invention, in a preferable embodiment, has a turning radius of just under 30 inches, a housing longitudinal length of approximately 8 inches, utilization of six identical silver anodized antenna element halves (three elements), a physical weight in the shipping carton of less than two pounds, and a weatherproof housing which may optionally contain a rotor and preamplifier.